High-pressure fluid pump



April 3, 1945. w. TvT BB 2,372,694

- HIGH PRESSURE FLUID PUMP Filed Feb. 4, 1942 s Sheets-Sheet 1 INVENTOR."

vATTORNEYS April 1945- W.T. TABB I HIGH PRESSURE FLUID PUMP 3 Shets-Sheef 2 Filed Feb. 4, 1942 INVENTOR.

P201121 1" Ta BY Whm ATTORNEYS April 3, 1945. T, TABB 2,372,594

HIGH PRESSURE F LUID PUMP Filed Feb. 4, 1942 5 Sheets-Sheet 3 I fa x/a J 4Z5 Ww/vlsflg g g mall. 8w M Patented 3, 1945 the latter is caught HIGH-PRESSURE FLUID PUMP Warner T. Tabb, Brooklyn, N. Y asslgnor, by mesne assignments, to Reconstruction Finance Corporation, New York, N. Y., a corporation of the United States Application February 4, 1942, Serial No. 429,464 21 Claims (Cl. 10341)' The present invention relates to a high pressure fluid pump and'method of makingparts thereof and, more particularly, to such apparatus adapted for use in fuel injection system for internal combustion engines such as those of the Diesel type.

A: general object of the invention is the provision of 'suchapparatus which can readily and economically be manufactured in quantity production with interchangeable parts, easily assembled and effectively andefllciently used.

A more specific object of the inventionis the provision of such pump structure so constructed and arranged as to necessitat quite accurate fitting between mating parts of plunger structure and associated casing means structure, such as bushing structure, of only one relatively short portion of the length thereof, e. g., of only the port section of a plunger in a plunger bore, and with suitable provision of a low pressure fluid leakage chamber to avoid high pressure leakage.

An additional object is the provision in such pump structure of structural features permitting during assembly of parts of proper self-alignment of the port section of the plunger in the bore without. detrimentally aflecting substantially low pressure fluid-tight sealing.

Other specific objects of the invention are the provision in such pump construction of certain structural features whereby simplicity in mantriacture is assured such as by separation of fits of parts that determine the efficiency of port operations'or closures ailecting pump delivery characteristics from fits of parts that may eliminate leakage of i'uelinto the pump sump or to areas outside the pump other than the low pressure fuel supply system making for ease in attainment of such fits; possible intermixing of fuel and low pressure fuel supply system and intermingling of fuel and lubricant is substantially eliminated, such auxiliary fits providing for relative sliding of parts to permit free relative longitudinal sliding action between plunger structure and chamber structure and self-alignment of the latter with the former independent of self-alignment of plunger structure in the bore and without interfering with the latter.

Another object is the provision in such a structure of a collar circumambient of the plunger spaced radially thereof with means therebetween providing a substantially low pressure fluid-tight sealand permitting. longitudinal movement of the plunger relative to the collar, the collar having a substantially low pressure fluid-tight seal with casing means such as a plunger bushing to form a leakage chamber preferably vented to a low pressure fluid passage, while providing for self-alignment of the plunger in associated structure.-

A further object is th provision in such a structure of certain plunger structure provided with a plurality of fluid ports adapted selectively to be brought into communicative position with respect to. low pressure fluid passage and selective interengaging means between plunger and casing means for permitting setting of the plunger in one of a number of different positions for delivery of a definite quantity of fluid in each position.

Still another object of the inventionis the provision of plunger biasing means which may seat directly against casing means or structure in 35 abutting relation thereto, and also against abutlubricant, even though the latter may be under some pressure in the pump casing such as the sump, is substantiallyeliminated; and high pressure fuel leakage from cooperating plunger and bore structure may be efllciently collected and returned to the low pressure fuel supply system with avoidance of dilution of fuel by lubricant and'inflltration of latter into the former.

itfurther more specific object is the provision of 'such pump mechanism characterized by a fuel leakage chamber and closure therefor provided by structure having surfaces readily fitted to casin: means structuresuch as a plunger bushing and'plunger structure independently of and aux-' iliary to the ntting of the plunger structure in the bore whereby high pressure fuel leakage from and may be returned to ment means on the plunger with the provision of self-centering means to avoid cooking of the p n er.

A further, object of the invention is the provision of such a structure characterized by cooperation of the plunger biasing means and low pressure leakage chamber structure whereby the former holds the latter against casing means structure with a substantially low pressure fluid guidance also serving to cooperate with the collar and associated structure to hold the parts togetherpwith' thecollar or means thereon serving as one abutment means and structure on the plunger servingasanother.

An additional object is the provision of abutment means on the plunger characterized by a swiveling arrangement whereby pressure of a plunger biasing spring such as a helical spring around the plunger is equalized and cocking of the latter avoided; such abutment means also preferably being quickly demountable by virtue of the provision of circumferentially confined means or members, e. g., balls held in a groove or against a shoulder on the plunger by a collar or skirted member.

Another additional object is to provide a simple and efiective method of producing a pump element, such as a plunger or piston, or casing means as a bushing constituting the pump cylinder or barrel, characterized by first sizing as by machining and surfacing an unbroken surface thereof to obtain a finished mating surface for proper cooperative operation witha finished mating surface of a companion pump element, and as a final step in the operations upon such surfaces removing, such as by grinding, a portion of the sized finished surface to form a port having a sharp accurate effective or working edge.

Also another object of the invention is the provision of efileient low and high pressure gasketing of a plunger bushing in a casing bore whereby eflective and simple low pressure fluid sealing does not interfere with proper positioning of the bushing and high pressure sealing may cooperate with a plug of a discharge conduit system accurately to limit its mountation in the pump here or predetermine its position therein.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements and arrangement of parts, and the several steps and the relation ofone or more of such steps with respect to each other for the production of certain elements or parts thereof, all as exemplified in the following detailed disclosure,,and the scope of the application of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken'in connection with-the accompanying drawings, in which: g

Fig. 1 is an elevational sectional view with parts broken away of easing means; a pump plunger and associated structure of one modirition and parts broken away of a pump plunger and associated collar or casing means and substantially low pressure fluid sealing means adapted to provide a leakage recess or chamber, constituting a modification of similar structure shown in Figs. 1 and 4;

Figure 5a. is a view in cross-section and with partsbroken away of a portion of a pump plunger and an associated sealing means;

i Fig. 6 is an elevational view with parts in section and parts broken away of a pump plunger [and associated collar and bushing with substana n e of th P ng r'in the bore, constituting a modification of similar structure shown in Figs. 1 and 4; and

Figure 7 is a view in cross-section of a portion of a modified form of pump including a two element pump plunger.

The present invention is adapted for incorporation in a pump of the general type disclosed in Purdy United States Patent No. 2,166,876 of July 18, 1939, which as more specifically explained therein constitutes an apparatus adapted for connection to a substantially low pressme supply system such as a supply tank of fuel oil and supply and venting conduit means. In apparatus of that type there may be provided a casing structure having a substantially axially arranged bore therein in which is mounted suitable metering valve structure through which low pressure fuel may communicate through passages to a pm. rality of pump plunger bores, one for each cylinder oi the engine; arranged circumierentially of the axial bore with, if desired, such pump plunger bores being provided by suitable plunger bushings mounted in circumferentially arranged holes in a casing, the casing and bushings comprising casing means. These pump plunger bores may further be suitably vented to low pressure fuel supply or a chamber connected thereto cooperating in the obtainment of substantially instantaneous cut-off of fuel under highpressure supplied from suitable nozzle structure to each of the engine cylinders. Each pump plunger, bore has associated therewith a suitable'pump lunger for reciprocative action therein and plunger op erative means such as a suitable cam device common to the plurality or pump plungers for successive operation thereof which latter structure may be located in a chamber in the casing structure with the chamber serving as a pump sump. The present invention is concemedwith the easing means in which the pump plunger bore is formed, the pump plunger reciprocatively mounted therein, spring rigging associated with the latter for biasing it in an outward position and associated structure.

Referring to the drawings, like numerals refer to like parts throughout. A casing in formed if desired of metal may, in accordance with one modified form of the present invention, be provided with a bore ll counterbored to provide a shoulder 12 preferably tapered, that is conforming to the surface of a truncated cone as shown, and further counterbored to provide an additional shoulder l3 which may have the surface thereof lying in a plane substantially normal to the axis of the bore. Inward of the high pressure end the bore II is preferablyv internally threaded as shown at I4 and the outward end thereof is counterbored at l5 to receive plunger spring rigging, cam follower and associated structure. A relatively low pressure fluid passage l8 is formed therein communicating with thebore .II and adapted to be connected through suitable passages and metering valve structure to a relatively low pressure fluid supply and may serve bore. u, snugly if desired, inwardly of the shoulder l3 such as at, I! for proper locationofthebushinginthecasingand setbackina midsection thereof such as at 20 to provide a shoulder 2| to cooperate with the bore shoulder I2 with'the interpositioning therebetween of ahigh pressure gasket 22, formed of any suitable material such as, by way of example, dead soft copper. The bushing i8 is further set back to provide a shoulder 23 adapted to cooperate with the bore shoulder l2 and between the latter two shoulders is confined 'a low pressure gasket 24 formed of any suitable material such as, by way of example, Babbitt metal. In the preferred may be tapered if desired. Further the gasket.

form the gasket 24 is made substantially rectangular in section and deformed (to the shape shown) by the tapered seat I: when the main 24 may be provided with a tapered face to cooperatewith-the tapered shoulder but adapted to be further deformed when the bushing is seated in the casing bore thereby to obtain substantially low pressure fluid-tight sealing.

The gaskets 22 and 24 may, if desired, be

formed of similar material that may be relatively resistant to deformation but capable thereof, or relatively softer material readily capable of deformation, so long as the seating area of gasket 22 is substantially greater than that of gasket 24. The latterfeature assures that gasket 24 while providing a substantially low pressure fluid-tight seal will not prevent a proper seating and substantially high pressure fluid-tight sealing at gasket 22 when the bushing |8 is forced into the casing bore II to a desired position determined by the cooperating shoulders l3 and 2| and gasket 22. The arrangement would be such that the low pressure gasket 24 would be adapted to be considerably deformed, relatively speaking, by p-.

sitioning of the bushing in casing, whereas the high pressure gasket 22 which serves to determine the longitudinal position of the bushing in the casing is not appreciably deformed by the locating operation. Further, a substantially high pressure fluid-tight seal 'may be attained at shoulders and 2| with the omission of gasket 22 by providing a lapped joint between complementary shoulders thereat which would serve to attain the desired seal and determine position of the bushing in thecasing with the gasket 2 being deformed to attain the low pressure seal.

The gasket 24 may be made of materlalsofter by shoulders such as at n and a to some a substantially low pressure fluid-tight seal without objectionably interfering with the desired.

locating or positioning of the bushing in the casing. By virtue of such structure it is not and as shown it may be spaced from the bore wall between paired shoulders l3, 2| and I2, 23 and also outwardly of the latter thereby'simplify- I ing manufacturing. As a result the bushing .is

a by recessing the high pressure end of the bushsealed into the casing at two different places simultaneously by the single act of sliding 0r forcing the bushing into the casing toa. predetermined position (where it is to be held) and such locating is determinedby only one pair of cooperating shoulders making for convenience in dimensioning and manufacturing to'toler-f ances. Additionally, necessity of carefully aligning thesurface of shoulder 22 with any cooper- 1 rating casing surface (as would be required if a considerable area of flat gasket surface seatin on opposed shoulders was used in lieu of the deformation feature characterizing the present invention) is eliminated.

Further high pressure sealing may be attained ing I! such as at 25 and this recess maybe so formed as to provide a shoulder 26 substantially normal to the axis of the bushing and a tapered shoulder 21 substantially conforming to the surface of a truncated cone. A gasket 28 of suitable deformable material such as, byway of example, dead soft copper, which may be initially substantially rectangular insection is compressed within 7 the recess 25 with its outside surface .29 engaging the wall of the bore one flat surface engaging the shoulder 26 and a portion deformed to conform to the tapered -seat 2'|.- This deformation O is attained by the positioning of aplug 30 in the high pressure end of the bore H such as by threaded engagement therein with the end of the plug engaging the other flat face of the gasket 28. The plug 30 thus retains bushing |8.in position in ythe bore II and is provided with a central openthan that from which the high pressure gasket ends.

22 is formed, such as relatively soft deformable not be essential to make the shoulder |2 tapered or of other sl'iape initially to provide a relatively ing which may have a portion thereof shaped to provide a seat for a check valve 3| whichcommunicates with a bore in the plug adapted to reeeive a couplingmember' connecting thereto suitable conduit means leading to suitable nozzle structure in the wall of an engine cylinder (not shown).

The extent to which the gasket 28 may be compressed isiimited and ac'cordinglyit may be used with the associated structure accurately to limit the insertion of the plug 30 into the bore due to the fact that after the gasket is deformed to the shape shown flat surfaces'of considerable area are engaged byshoulder 26 and. the end of the small seating area since obviously a greater seating. area, such as provided by. a relatively wider,

. substantially flat transversely extending shoulder,

could be used with the attainment of similar In any case the arrangement is such thatcooperating shoulders such as at I3 and 2| provide a substantially high pressure fluid-tight seal and determine the position of the bushing in the easing and a gasket such as that at 24 is deformed plug 30. Obviously the gasket 28 may be initially formed with a bevelled surface to cooperate with mation as the plug 30 is forced into the bore Ill with respectto the high pressure gasket 2|,

as in the case of gasket fl, reliance-maybe placed dimensions of associated structure relating to ecessary toyhave the bushing carefully fitted v into the bore |l throughout the length thereof the tapered surface 21 of the bushing I! but provided sufllciently oversized so as to obtain deforthis feature. Fundamentally this feature is characterized by deformation of the gasket during an portion of the operationof forcing the plug into bore H while enabling plug 3| flnallyto find a. positive seating surface of sufficient 'area so that termination of its movement into the bore is well defined and accords with a predetermined position. The final seating surface'of area greater than the initial seating surface may here be provided by the relatively large area of final seating of the surfaces of the gasket 28 and the shoulder 25' and this in cooperation with resistance by the 'gasket material to deing surface such as 26 and likewise similar misalignment of the end surface of the plug with the end surface of the bushing such as suggested in Fig. 4 would not give rise to any problems and r of course there is no problem ofdeakage here involved.

'The tapered seating surfaces 42 and 21 have been chosen as a matter of convenience whereby the initial small seating area permitting increase thereof during gasket deformation is readily obtained. Obviously, however, this may be obtained by other arrangements such as stepping the shoulder whereby the seating surface for the aevaeoe or tubular plunger follower having a base portion It recessed at 31 to receive a follower roller 3| mounted on a pin 39 disposed in a hole traversing the base 35 with the roller 38 engaging a suitable cam surface 40 which may be located in a pump sump or cam chamber. The base 38 of the follower 35 may suitably be pierced longitudinally to avoid theformation of a vacuum -or compression chamber in the counterbored portion I5 during reciprocative operation of the follower. A land 01- projecting portion 4! is provided on the base 38.

A pump plunger 42 of any suitable design may be suitably fitted in the plunger bore 32 of the bushing ll and preferably comprises a high pressure end 43, a port section, a sealing section '35,

and an outward operable end 45 for engagement with the projecting portion 41 of the follower for inward movement thereby.

Circumambient of the plunger 42 is arranged an auxiliary bushing section 47 which may be a collar radially spaced therefrom and having a flange M in substantially low pressure fluid-tight initial seating is inone or more transverse planes but of sufliciently small total area to permit read deformation of the gasket thereafter and provide for increase of the seating surface such as by bringing into operation additional seating surfaces in transverse planes upon such further deformation.

It will thus be'seen that with respect to the gasketing arrangement proposed above there is provided a structure wherein a bushing is sealed to a casing against low pressure at one place without locatively determining the position of the bushing with respect to the casing, is sealed against high pressure at another place and its position with respect to the casing locatively-determined thereat, and issealed against high pressure but not located with respect to the caring at a third place, andjn addition a plug holding the bushing assembled in the casing is first sealed and finally locatively positioned at that third place.

' The bushing I8 is provided with a plungcr bore 32 which, if desired, may have the high pressure end thereof counterbored as at 33 with a passage 34 communicating between the counterbored portion 33 and the passage 17. Such a feature is disclosed in the Tabb et'al. United States Patent 2,247,421 of July 1, l9dl, wherein it is explained that fluid under pressure in front of the pump plunger is vented through such passages to reduce the pressure of the fluid in the conduit to the engine cylinrer suficiently, to permit a spring biased valve '11 nozzle structure to close thereby cutting ofl fluid discharge from the nozzle. Such a feature, however, is not essential to the structure of the present invention.

In the counter-bored portion 15 of the 'boreof the casing I0 is reciprocatively mounted a skirted sliding engagement with the sealing section #25 of the plunger 42 to provide a leakage recess 49. The main bushing section 18 is provided with a shoulder 5i which is engaged by one end of the collar 4! preferably. with a transverse sliding fit to assure the formation of a leakage chamber iconstituted by recess 49 and freely permitting selfalignment of the plunger with respect to the bushing and with respect to the collar when being mounted into the casing to assure proper alignment of all such parts, and proper cooperative functioning thereof even though in production there has been, as desired, independent sizing of plunger and main bushing section, and the plunger and collar. The so-formed leakage chamber may be vented in any suitable manner such as by a passage 5I- communicating with a passage 52 in communication'with passage it. The passage 52 may be formed in any suitable manner after machining, surfacing and hardening of the main bushing section [8 such as by grinding a transverse slot therein which does not break through the plunger bore surface, and the bushing may be ported at 53, after suitably finally sizing the bore 32 such as by fitting or lapping a plunger therein; This may be accomplished.- by grinding or otherwise cutting a transverse slot more deeply into the bushing until a port 53 of desired dimension is broken through mm the bore 32, such so-formed port having sharp effective or working edges from which burrs may be stoned oif if;necessary.

The collar 41 may be held in engagement with the main bushing section 18 by any suitable means such as by members secured to the main bushing section or supported from the casing but preferably is held in position by means biasing the plunger which may be a helical spring 54, one end of which abuts or seats against flange 55 on a cup-shaped member 55 having a flange 5! en.- gaging against a shoulder 58 on .the collar fill. Other abutment means for the other end of the spring 54 are mounted on the plunger 42. Such means may comprise a skirted'collar 59'having an inwardly facing tapered surface 60, such as a substantially spherical surface as shown, adapted to cooperate with'a tapered surface 6| within groove 'in the operable end 45 of the plunger cooperates with the skirted collar 59 to confine between the shoulder as within the collar is and .a shoulder 66 formed by'groove 64 any suitable element such as a ball 61 or a p r y thereon ring of relatively soft material or helical spring Q torus might be used to advantage since they would adjust themselves to such conditions. Such structure permits ready demountation from the plunger of the parts including the spring which is attained by compressing the spring 54 to permit the collar 59 to be moved inwardly on the plunger sufficiently to free the securing means such as the balls 51.

Means are preferably provided On the plunger. to cooperate with the flange 43 of the collar 41 so that a sub-assembly may be provided. Such means may constitute a pin 53 located in the recess or chamber 43 and loosely held in a transverse hole 69 in the plunger 42 by the collar 41...

As a consequence the plunger 42; pin 68, collar 41, member 56, spring 54, skirted member 59, cup member 62 and balls-51' may be assembled into a sub-assembly the parts of which securely remain in relative positions prior to assembly thereof with the casing or main bushing section and cam follower thereby facilitating and. simplifying assembly of the parts of the pump mechanism. The pin 66 also may serve as a guide pin for interengagement with casing means as hereinafter. ex-

plained and for a purpose indicated.

The plunger 42 preferably is provided witha plurality of. sets of supply and venting ports selectively to be used for delivery of different quantitles of fluid. The set of supply ports may be three in number arranged circumferentially of the plunger about 120 apart as indicated in Figs.

. 2 and 3 and may comprise ports 10, 1| and 12 each having a working or effective controlling edge 13 located at a certain point along the plunger. A set of venting ports are paired with the supply ports and may comprise the three similarly arranged as indicated at 14, 15 and 16 each of which has an effective or working edge '11 also arranged at'a certain point. The distance between the edges-13 and 11 of any pair of ports angularly positioned for cooperation with effective or working edges of the port or ports ofa passage or'passages leading intothe plunger bore may determine the capacity of one pump cylinder for that particular plunger position. This distance minus a corresponding distance between the effective or working edges of the casing means port or ports is the length of the eflective stroke of the plunger.

plunger ports may be located at a distance apart differing from that for other pairs of ports, which as shown only by way of example difler for any one pair of ports. With one port provided by passage 53 in the bushing serving both as a bush- ,ing supply port and bushing venting port for each plunger bore, as shown by way of example in the structures depicted in the drawings, this distance .between effective edges of bushing ports is the If desired, the effective working' edges of a certain pair of supply and venting the distance between bushing port edges 531 and 532. As desired-the supply ports 10, 1| and 12 and venting ports 14115 and 16 may be formed with their edges respectively arranged as shown or I may be formed with all of the eifectivetrailing 'edges 13-13 of the supply ports arranged in the same transverse plane and effective leading edges 11-41 arranged in different transverse planes. A further alternative is the arrangement of all lead- 10 ingedges -11-.11 in the same transverse plane and the trailing edges 13-13 in different transverse planes.

The difierent pump capacities provided by the different selective plunger positicnings may be 15 attained by providing a plurality of passages similar to 53 in a single bushing with the effective one of such bushing ports by selective angular positioning of the plunger.

Such novel port features obviously may be incorporated in plungers of the axial passage type wherein a longitudinal passage-18 extend substantially axially from the high pressure end 43 through'the port section 44 of the plunger, and this may be brought into communication with the go'ports 10, 11, 12, 14, 15 and 15 in any suitable manner such as by drilling holes 1919 such passage 13 and a hole 19 cooperatively serve as a fluid way between high pressure end 43 and a port. However, it will be understood that other as methods of providing ways for passage of fluid between such ports and high pressure end 43 of the plunger may be utilized in practicing the invention such as, for example, by forminggrooves in the cylindrical surface of the plunger to extend between thehigh pressure end of the plunger and the ports. I

These sets of supply and venting ports are provided in the port section 44 of the plunger subsequent to the treatment and sizing or lap 45 fitting of the plunger port section in the port.

. section of the plunger bore ormain bushing sec-- to give greater hardness and a molecular structure of the cylindrical surfaces more suitable for hardening by nitriding'. After heat treating the cylindrical surfaces are preferably ground to remove the extreme outer surface to permit more effective nitriding. and incidentally for closer sizing, This grinding, however, is to dimensions which are still oversized for theplunger and undersized for the bushing. The elements are then subjected to a nitriding treatment wherein ammonia gas causing hardening. After nitriding a final grinding of the cylindrical surfaces is performed to dimensions not quite the final size, there being provided an allowance of a few ten-thou- 7 sandths of an inch for lapping to ive a perfect fit of the mating parts. After fitting the mating parts such as by lapping, the ports are ground into the cylindrical surfaces as a final step of operations on such surfaces so that uninterrupted surfaces are had for sizing or fitting the mating 6 w asvaeea.

Y parts together whereby sharp, definitive effective or working edges of ports are assured. This avoids dulling of such edges by machining, grinding and lapping since in lapping, lapping compounds tend to collect atedges and to form a slight tapering of cylindrical surfaces at such points, and in machining or grinding surfaces the operations tend to remove excessive amounts of material at the edges of interruptions of the surfaces. For example, pressure of a grinding wheel against the work is slightly relieved at the edges of interruptions so that there is a tendency excessively to remove material thereat.

In so forming such plungers characterized by the provision of fluid passages from the high pressure ends of the ports such as the axial passage l8 and the holes T9--l9 these may be formed such as by drilling prior to the hardening, grinding, lapping and final porting. This is permissible since the holes IS-l9 are of less dimension than the width between the opposed edges of any one port. Accordingly even though in grinding and lapping excessive material is removed adlacent the edges of the holes 19-19 the dulled or imperfect surfaces adjacent thereto will be roimd off in the formation of the ports. Further, the axial passage. "and the holes 19 19 may be provided at any time during the process of formation even subsequent to the porting. For

example; a portion of the area of the high pressure end of the plunger may be protected from hardening such as by plating or painting and then subsequent to the hardening the axial passage 1'8 may be drilled and the holes 19-48 may be drilled either priorto or subsequent to the ilnal sizing or lapping and of course prior or subsequent to'the porting. Further if it be desired to drill the passage 18 prior to hardening protection for the surface thereof may be provided by plugging with clay or otherwise, or the surface of the passage I8 may be protected by painting with certain paint which prohibits infiltration of ammonia gas. As an alternative, when the passage It is formed prior to hardening, the surface thereof may be left lmprotected since in drilling the holes 19"|! no diihculty is found in piercing through the hardened surface or crust of the axial passage 18 since this crust in the case of -nitriding is quite thin. It is to be understood ll prior to hardening and then after hardening,

further grinding, lapping, and finally porting. the

holes IQ-1! are drilled through from the portsinto axial passage 18; but in any case, regardless of what variations ofprocedure'are adopted, the.

formation of the ports inthe cylindrical surfaces of both the plunge and the bushings is always done subsequent to he treatment and the final mechanical working of those surfaces (such as lapping and fitting) to assure the obtainment of sharp accurately operative eifectiveworking port edges. "Obviously the formation of the passages El and 52 and the formation, such as by grinding, of the port passage 53 in the main bush ing section It may be accomplished in a variety of ways "as to time and method of formation, similar to thosepointed out above in connection with in the plunger.

the formation of'an axial passage 18 and passages 79-19 in the plunger. Thusthe two basic pump elements, the plunger or piston and the bushing constituting the cylinder or barrel, are

5 finished and ported by a similar procedure of the present invention.

The outward end of the main bushing section I 8 may be provided with a' flange 88 circumambient of the plunger 42 preferably within the in chamber and this flange may be provided with three pairs of diametrically opposed longitudinally extending ways or slots 8l8l with each pair arranged about 120 from the successive pair similar to the arrangement of the pairs of ports A pair of opposed slots 8i, 8| are adapted to receive the opposite ends of the pin 68 as shown in Figs. 1 and 4 for positioning 1 of a pair of supply and venting ports of the plunger in selected communicative relation to the 20 Port end of passage 53. Accordingly the plunger 42, when being mounted with the other parts of the sub-assembly relative t the bushing section l8 and easing l0, may be placed in a selected desired operative position in the plunger bore whereby the guide pin 68 serves not only as means to hold the parts of the sub-assembly together but also as an indexing and guiding means. After placement of the sub-assembly in the bushing section l8 of casing III the follower 35 is then inserted in the counterbored portion l5 of the casing bore.

It will be understood that any suitable interengaging means between the plimger and easing means may be, used for this purpose of indexing and guiding. For example, only one pair of diametrically opposed slots Bl, 8| need be formed in the flange 80 and the pl er may be provided with three transverse holes 349, as indicated in Fig. 4, so arranged as to provide for difi'erent i0 selective placement of pin 68.

Although the structure described above for the provision of the leakage chamber 49 is preferred, obviously it is not essential to form the collar member I! separately from the bushing or casing 5 means with the provision therebetween of a substantially low pressure fluid-tight transverse sliding fit. The desired provision for self-alignment of the plunger 42 may be attained by resilient means. In, Fig. 5 such a structure is'illustrated 50 wherein the collar member may be a flange portion 82 formed integral with the main bushing section or casing means. A groove 83 may be formed in the sealing portion of the plunger J2 and a resilient ring I of suitable material such as neoprene may be seated therein with its outer surface slidably engaging the inner wall of the portion 82 ins-substantially low pressure fluid tight sealing manner. As shown in Figure 5a, a ring of resilient material llcmay be fixed relative to the portion 02 with the provision of a substantially low pressure fluid-tight sliding fit with the sealing portion 45 of .the plunger 42, thus being used as a flange in lieu of that at 48 illustrated as being made integral with the collar 41.

Further it will be understood from Fig. 6 that the surfaces at the cooperating ends of the bushing section it and collar ll need not of necessity be lap-fitted if a gasket II of any suitable material permitting relative transverse movement of the collar and bushing section is interposed. This gasket may, if desired, be formed of relatively resilient material such as neoprene.. It-wlll fur- I ther be understood that the self-alignment of 7b plunger structure relative to casing means structure wherein such independent fittings of the ing means structure bore and at the outward end of the casing means structure constituting a closurefor the" leakage chamber maybe provided by a structure wherein the bushing section I! and collar 41 are rigidly made integral with each other while perinitting the use of a rigid closure flange such as 48, if the plunger structure comprise sections which may be movable relative to each other transversely. As illustrated in Figure 7 atwo part plunger structure 42a, 42!) might be plunger structure at the port section of the cas- 1 may predetermine the position of the plug in the high pressure end of the casing bore I I. Such predetermination of position may additionally be attained, as indicated, by causing the end of the plug 30 to engage the high pressure end of the used within the scope of the invention wherein f the plunger part 42a is aligned in the port section of the bore 32a and is abutted against the other section 42b'which is slidably fitted in the closure flange 48a and with theiruadjacent ends in abutting relation so that the plunger ported section 42a may be forced inwardlyby the other section and return stroke of the former obtained by suitable biasing means such as a spring 54aat the high pressure end of the plunger structure. The pin 68 may be received in a groove 92 in the end of the section 42a to facilitate adjustment and indexing of the plunger section 4212.

If desired, the provision for centering'and/or balancing action of the spring 54 may be omitted from the abutment means mounted On tlfe plunger 42 and additionally the means for biasing the collar 41 with a transverse sliding fit to the bushing l8 may be modified all as illustrated in Fig. 4. By way of example a plate 88 having a spring seating flange 81 may be mounted on the end 46 of the plunger 42 by placement of suitable means such as a split ring 88 in the groove 64.

The opposite end of the spring 54 may be seated directly against casing structure rather than means mounted on the collar 41 such as by seating it against a-shoulder 89 on the'casing ll and the collar 41 may be held in engagement with the casing means or bushing 18 by an auxiliary spring 90 seated at one end on plate 86 and at theother end against the collar 41 or the flange 48 thereof. In such a case the sub-assembly would include the helical spring 94 and the plunger biasing spring 54 would be mounted as a separate element at the time of assembly of the sub-assembly in the bushing or casing means.

Obviously the helical spring 90 supplements the biasing of the plunger by the spring 54. Other and further modifications of such structure and associated parts within the scope of the invention will readily occur to those skilled in the art.

The cooperating tapered surfaces SI and il of the abutment means mounted on the plunger for the spring rigging are preferably shaped as described but not necessarily so. The surface Bl could be somewhat spherical having agreater radius of curvature than the spherical surface ill or the latter might be made conical similar to the-illustrated shape of the surface BI and the latter could be convexed to cooperate therev with. Resulting line contact or at least small area of contact are desired for attainment of centering and/or balancing abtion of the springbushing l8 such as at 9| as shown in Fig. 4 after 't-e gasket 28 has been suitably deformed and depressed in the recess 25. The provision of the ga'sketing 28 makes possible tire use of such structure without necessitating accurate lining up of cooperating surfaces of plug 30 and bushing section 18 at 9 I.

It will be understood that the following terms as used in the specification and claims are intended to have the following meanings. "Casing means" may include plunger bushing means if used and a surrounding casing or may refer to a casing alone when the plunger bore is formed directly therein. Bushing means may include a main bushing seated in the casing and an aux liary bushing means section which may be 54 to avoid cocking of the plunger 42 which has been provided with only a relatively short accurate sliding fit in the plunger bore. Furt'-er other types of cooperating surfaces may be .utilized.

for a s milar purpose, for example. a cowidal surface similar to the spherical surface shown. as well as a s ort conical surface cooperating with an extended conical surface, or a sho t spherical surface cooperating with an extended spherical surface of similar radiiof curvature,

a collar having a substantially low pressure fluld tight seal or transverse sliding fit with the main bushing. The "flange on the collar engaging the plunger may be made of any suitable mate rial such as the metal from which the collar may be made and integral with or separate therefrom, or of resilient material such as neoprene whereby a transverse sliding fit between a leakage chamber collar and easing means need not be provided.

Abutmentmeans" refers to any and all structure 7 whichin and of itself or through associated or interposed structure limits or stops movement of biasing means such as a spring and against which the latter bears either directly by direct contact therewith or indirectly through interposed structure. The term outwardly" refers to direction awa from the pump casing, that is toward the cam follower or operatively engaged end of the pump plunger; and "inwardly refers to the reverse direction, that is into the pump casing or bushing therein since t e pump plunger is forced inward or into the plunger bore on the working stroke. Relat vely low pressure fluid" refers to fluid fed to the pump such as by a suitable system which may include with'a fluid supply a relatively low pressure transfer pump and "high pressure" is re atively higher pressure produced by acticnof the pump of-the presentinvention. Substantially fluid-tight seal and "substantially fluid-t ght flt respectively refer to structural seals and fits which substantially prevent leakage or permit only ver little or negligible leakage at the indicated pressures such as some minor or unimportant seepage or fluid film transfer.

In operation, with the parts assembled and positioned as shown in Fig. 1 and a low pressure fluid or fuel supply connected with passage I such as through suitable metering valve structure, the cam surface of cam'plate 40 upon rotation of the latter will permit the pump plunger .to be forced by the spring biasing structure outwardly out of bore 32 until the supply port II is opened to the-passages i3. 52 and J4 permitting low pressure fuel to enter through the supply port, opening I! and plunger passage 18 into the bore ahead of the high pressure end 41 of the plunger. Upon further rotation of the. cam plate all the follower 35 is forced inwardly against the action of the spring 54 forcing the plunger into the bore 32 until the effective trailing edge I8 of the port 10 passes the bushing port edge "I v and thereafter to compress the so-supplied fuel in the plunger bore. This fuel under pressure will unseat the valve 3| in the plug and permit sufiicient pressure to be built up in the conduit leading to the nozzle whereby to unseat a valve therein so that the fuel willbe sprayed into the engine cylinder. On further movement of the plunger it the effective or leading edge 11 of the venting port 14 will pass the bushing port edge 5I2' quickly to vent fuel under high pressure through plunger passage 18, opening 19 and port I 14 to fuel supplyto obtain substantially instantaneous cut-off of fuel supplied to the engine cylinder and accurate delivery of a predetermined quantity thereof. Upon further rotation of the cam It! the follower will be permitted to recede from the counterbored portion l5 as the biasing spring Bl forces the plunger 42 outwardly again bringing the supply port 10 into communication with the passage 53, and thereafter the cycle-is repeated. 1 V By virtue ofthe structure of the invention described substantially noleakage of fuel from the high pressure system between the engine cylinder and pump will occur past the plunger and bushing into the pump sump (in which the cam II and other operating parts are located) and lubricating oil therein. Infiltration of lubricating oil into the low pressure system is likewise avoided even if a fair amount of pressure of lubricating This makes possible manufacture of parts to gauge inspection as contrasted to individually. fitting of parts by lapping on assembly.

Asa

' result a so -called selective assembly system in oil exists in the pump sump. Avoidance of such leakage is accomplished by means of the auxiliary .bushing section or collar 41 and the leakage chamber 49 provided thereby and vented to the low pressure supply by passage 5|, so that any leakage past the plunger into this chamber is automatically returned to the low pressure system. The fit of the collar I! through its flange ll or similar structure with the sealing section I! of the plunger is independent of the fit of the portsection 44 of the plunger in the bushing bore 32 so that the latter need be accurate within a limited tolerance only adjacent to the ports and to'provide a reasonable lineup of parts. This fit between collar flange l8 and the plunger is of necessity only of the low pressure type and therefore is a, comparatively easy fit to obtain and maintain, and makes readily practicable interchangeable or selective manufacture of parts and assemblies. In fact the length of the surface which the cooperating parts are each made to a certain dimension with a reasonable tolerance and the parts are paired so that the fit of any two paired parts may be much closer than the tolerances permitted is possible which may make unnecessary accurate fitting at the time of assembly. Such a system will include mating of parts which may be easily accomplished in commercial production. By this is meant the manufacture of the parts to predetermined gauge dimension within a reasonable tolerance range. As a result, the dimension of. some of the parts will be that dimension plus, others possibly practically to that dimension, and still others that dimension minus. Such parts will accordingly be separately grouped or classified according to such dimensions as will the parts with which they are to'fit, thus constituting the referred to mating. Such so-classified parts will thus be interchangeable with any other part selected from the same grouping which will permit utilization of standard methods of interchangeable menufacture and a resultant elimination of manufacturing difliculties usually acceptably recognized in the production of pumps of this type.

It will be noted that the construction is featured by a plurality of mating parts wherein each mating is independent of others and of a single dimension as contrasted with plural or two dimension mating such as in pump construction where a plunger must beaccurately fitted to the bore at both the port section and the outward end of the bore. There, one dimension fitting controls the porting and the other dimension fitting controls the leakage between the plunger and bushing at the outward end of the bore. It has been found in manufacture of such latter constructions that after carefully fitting the plunger to the bore at the port section there often is not a proper mating of the plunger and bushing at the outward end of the bore such as to avoid excessive leakage. This difficulty is eiilciently overcome by the present invention.

The present invention further makes readily practicable a simple interchangeable assembly production wherein the, parts can be sized closely enough to gauge as to permit a multiplicity of 7 any one part, all to be classified-or grouped toof sliding fit between the collar flange 48 and the sealing portion 45 of the plunger 42 is preferably made comparatively short so that the lineport section N, the problem of obtaining satisfactory fit of these parts is greatly simplified.

i sliding fit of the plunger in the bushing bore 32 -may be relatively short that is throughout the gather in one group, and any one of that group to be interchangeable with any'other thereof in assembly of such part with any other cooperative part chosen from a group thereof. Thus the present invention is not only readily adapted to 'a selective assembly system wherein a multiplicity of any one part are classified into two or more groups as described above, but also to a simple interchangeable assembly system wherein the parts are of such construction as to permit classifying all of a multiplicity of any one part in a single group; both types of systems being practicable in commercial production of I pump structu're assemblies of the present invention with assurance of emcient operation thereof.

In view of the fact that only relatively. short mating surfaces of the pump plunger and bushing bore are essential to efficient" operation of the mechanism of the present invention and are desired for indicated reasons, provision has been made to assure at all ,times in assembly and operation a proper alignment of the parts with substantial elimination of possible transverse pressure against the relatively long section of the plunger between the port section thereof and its operative end. Accordingly the outward end of the plunger rides freely on a smooth surface of the follower 35 and provision is preferably made for balancing biasing action-oi spring 56 thereby avoiding possible cockingof the plunger. Accordingl provision is made for limited transverse movement of the plunger by reason of the construction of auxiliary bushing section or collar 41 or the sealing means interposed therebetween and in addition the provision of the swiveling structure in the abutment means mounted on the plunger and against which an end of the biasing spring seats. The above described cooperating tapering surfaces in that abutment means per mits a suitable swing of the spring seating 'mem her and thus tends to equalize spring pressure at all points circumambient of the-plunger.

It will thus be seen that the objects set forth above and those herein indicated are efiiciently attained'and since certain changes in carrying out the above-process and in the constructions set .forth, which embody the invention may be made without departing fromits scope, it is intendedathat all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense;

It is also to be understood that the following claims are intended-to cover all of the generic and specific features of theinvention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what 1 claim as new and desire to secure by Letters Patent is:

1. In a high pressure fluid pump the combination comprising; casing means structure having a bore and a relatively low pressure fluid passage port communicating therewith, a plunger structure slidably fitted into the bore in the vicinity of the passage port, said casing means structure having a section of the walls of the bore outwardly of the sliding fit radially spaced from said plunger structure, and means having a sliding flt with said plunger structure providing a substantially low pressure fluid-tight seal betveen said casing means section and said plunger structure to form a leakage chamber, the sliding fit of said plunger structure in the bore adjacent the port being independent of the second-mentioned sliding fit and one of said casing means and plunger structures being sectioned for permitting independent self-alignment of said plunger structure with respect to cooperating" casing means structure at both of the flts.

2. In a high pressure fluid pump the combination comprising, a casing having a bore and a relatively low pressurefluid passage communicating therewith, bushing means seated in the bore having a plunger bore and a relatively low 'pressure fluid passage communicating between the last-mentioned bore and the first-mentioned passage, a plunger slidably fltted into said bushing means in the vicinity of the last-mentioned passage,,said bushing means having a section outwardly of the sliding fit radially spaced from i said plunger, and means providing a substantially low pressur fluid-tight seal between said bushing means section and said plunger to form a leakage pressure fluid passage, one of said bushing means section and sealing means for permitting transverse movement of said plunger to align said plunger with said bore.

3. In a high pressure fluid pump the combination comprising, a casing having a bore and a relatively low pressure fluid passage communicating therewith, bushing means seated in the bore having a plunger bore and a relatively low pressure fluid passage communicating between the last-mentioned bore and the first-mentioned passage, a plunger slidably fltted into said bushing means in the vicinity of the last-mentioned passage, said bushing means having a section outwardly of the sliding fit radially spaced from said plunger, and means providing a substantially All low pressure fluid-tight seal between said bushing means section and said plunger to form a leakage chamber vented to a low pressure fluid passage, said bushing means section comprising a separable element having a substantially low pressure fluid-tight transverse sliding fit with the remainder of said bushing means providing forindependent alignment of said plunger in the bore and in' the leakage chamber bushing means section. v

4. In a high pressure fluid pump the combination comprising, a casing having a bore and a relatively low pressure fluid passage communi-' eating therewith, a bushing seated in the bore having a plunger bore and a relatively low pressure fluid passage communicating between the.

last-mentioned bore and the first-mentioned passage, a plunger slidably fitted lna said bushing in the vicinity of the last-mentioned passage, a collar circumambient of and radially spaced from said plunger outwardly of the sliding fit mounted in a substantially low pressure fluidtight manner relative to said bushing and for transverse movement relative thereto, and means providing a substantially low pressure fluid-tight seal between said collar and said plunger to form a leakage chamber. I

5. In a high pressure fluid pump the combination comprising, a casing having a bore and a relatively low pressure fluid passage communicating therewith, a bushing seated in the bore having a plunger bore and a relatively low pressure fluid passage communicating between the last-mentioned bore and the first-mentioned passage, a plunger slidably fitted into said bushing in the vicinity of the last-mentioned passage, a. collar circumambient of and radially spaced from said plunger outwardly of the sliding fit and having a substantially 'low pressure fluidtight transverse sliding flt with said bushing, and a flange onsaid collar outwardly of the radially spaced portion thereof having a substantially low pressure fluid-tight sliding fit with said plunger to form a leakage chamber;

6. In a high pressure fluid pump the combination comprising a casing having a bor and a eating therewith, a bushing seated in the bore having a plunger bore and a relatively low pressure fluid passage communicating between the last-mentioned bore and the first-mentioned passage, a plunger slidably fitted into said bushing in the vicinity of the last-mentioned passage, a collar circumambient of and radially spaced from said plunger outwardly. of the sliding fit V and having a substantially low pressure fluidtight transverse sliding fit with said bushing, and

a flange on said collar outwardly of the radially spaced portion thereof having a substantially low pressure fluid-tight sliding flt with said plunger to forma leakage chamber, said bushing hav ing a passage communicating between the leakage chamber and the last-mentioned low pressure fluid passage.

7. In a high pressure fluid pump the combination comprising, casing means having a plunger bore therein terminating in an outward end, a plunger slidably fitted into the bore, a collar circumambient of and radially spaced from said plunger outwardly oi the bore end, and means providing a substantially low pressure fluid-tight seal between said collar and said plunger to form a leakage chamber, one of said collar and sealing means permitting transverse shifting move ment of said plunger to align said plunger with said bore.

8. In a high pressure fluid pump the combination comprising, casing means having a plunger bore therein terminating in an outward end, a plunger slidably fitted into the bore, a collar circumambient of and radially spaced from said plunger outwardly of the bore end and having a substantially low pressure fluid-tight transverse sliding fit with said casing means, and means providing a substantially low pressure fluid-tight seal between said collar and said plunger to form a leakage chamber.

9. In a high pressure fluid pump the combine. tion. comprising, casing means having a plunger bore therein terminating in an outward end, a plunger slidably fitted into the bore, a' collar circumambient of and radially spaced from said plunger outwardly of the bore end and mounted in a substantially low pressure fluid-tight manner relative to said'casing means with an interposed resilient gasket permitting relative transverse movement, and means providing'a substantially low pressure'fluid-tight seal between said collar and said plunger to form a leakage chamber.

10. In a high pressure fluid pump the combination comprising, casing means having a plunger bore therein terminating in an outward end, a

plunger slidably fitted into the bore, a, collar.

circumambient of and radially spaced from said plunger outwardly. of the bore end and having a substantially low pressure fluid-tight transverse sliding fit with said casing means, and a flange on said collar outwardly of the radially spaced portion thereof having a substantially low pressure fluid-tight sliding fit with said plunger to form a leakage chamber. l

11. In a high pressure fluid pump the combination comprising, casing means having a plunger bore therein terminating in' an outward end, a plunger slidably fitted into the bore, a collar circumambient of and radially spaced from said plunger outwardly of the bore end and a, ring of resilient material fixed on one of said collar and said plunger and having a substantially low pressure fluid-tight sliding fit with the other to form a, leakage chamber and provide for independent alignment of said plunger in the bore and in said collar.

12. In a high pressure fluid pump the combination comprising, casing means having a plunger bore therein terminating in an outward end, a

plunger slidably fitted into the bore, a collar circumambient of and radially spaced from said plunger outwardly of the bore end and having a substantially low pressure fluid-tight seal with said casing means, and a ring of resilient materlal on said collar outwardly of the radially spaced portion thereof having a substantially low pressure fluid-tight sliding lit with said plunger to form a leakage chamber and provide for independent alignment of said plunger in the bore and in said collar.

13. In a high pressure fluid pump the combination comprising, casing means having a plunger bore therein terminating in an outward end, a plunger slidably fitted into the bore, a collar circumambient of and radially spaced from said plunger outwardly of the bore end and having a substantially low pressure fluid-tight seal with .said casing means, and a ring of resilient material on said plunger having a ubstantially low pressure fluid-tight sliding flt in said collar to form a leakage chamber and provide for independent alignment of said plunger in the bore and in said collar.

Id. In a high pressure fluid pump the combinetion comprising, casing means having a plunger bore therein terminating in an outward end, a plunger slidably fitted into the bore, a collar circumambient of and radially spaced from said plunger outwardly of th bore end, means providing a substantially low pressure fluid-tight seal between said collar and said plunger to form a leakage chamber, abutment means on said plunger outwardly of said collar and additional abutment means on said collar, and spring means confined between said abutment means holding said collar in a substantially fluid-tight fit with said casing means.

15. In a high pressure fluid pump the combination comprising, a casing having a bore therein, a bushing seated in the bore terminating in outward end and having a plunger bore therein, a plunger slidably fitted into said bushing, a collar circumambient of and radially spaced from said plunger and surrounding the outward end of said bushing, said collar having a substantially low pressure fluid-tight seal with said bushing, means providing a substantially low pressure fluidtight seal between said collar and said plunger to form a leakage chamber, and interengaging means between said plunger and said bushing in the chamber permitting sliding action of said plunger in a predetermined angular position, said interengaging means cooperating with said sealing means to limit outward movement of said plunger relative to said collar.

16. In a high pressure fluid pump the combination comprising, a. casing having a bore therein, a bushing seated in the bore terminating in an outward end and having a plunger bore therein, a plunger slidably fitted into said bushing, a

u collar circumambient of and radially spaced from said plunger and the outward end of said bushing, said collar having a substantially low pressure fluid-tight seal with said bushing, a flange in said collar outwardly of the end of said bushing having a substantially low" pressure fluid-tight sliding fit with said plunger to form a leakage chamber, the outward end of said bushing in the chamber having a substantially longitudinally extending slot therein and a guide pin on said plunger operatively disposed in the slot and cooperating,

with the flange on said collar to limit outward movement of said plunger relative to said collar.

1'7. In a high pressure fluid pump a sub-assembly comprising in combination a pump plunger, a leakage chamber collar circumambient of and radially spaced from said plunger, means between said collar'and said plunger spacing the 7 latter from the former and permitting relative longitudinal movement of said plunger and said collar, means on said plunger cooperating with said first-mentioned means to limit outward movement of said plunger relative to said collar, abutment meanson said plunger outwardly oi said collar and additional abutment. means on said collar, and plunger biasing means conflnedgbetween said abutmentmeans with said flr'stand second mentioned means in engagement.

. 18. In a high pressure fluid pump a sub-assembly comprising in combination a pump plunger, av leakage chamber collar circumambient of said collar outwardly of the radially spaced portion thereof having a sliding lit with said plunger. means on said plunger within said. collar cooperating said said flange to limit outward movement of said plunger relative to said collar, abutment means on said plunger outwardly of said collar and additional abutment means on said collar, and a helical spring disposed about said plunger and confined between said abutment and radially spaced from said plunger, a flange on 7 means with said movement limiting means in en gagement with said flange.

19. In a high pressure fluid pump the combination comprising, casing means having a plunger bore, spring abutment means fixed relative to said casing means, a pump plunger in the bore, a helical spring disposed about said plunger hearing against said abutment means, other abut ment means mounted on said plunger having a tapered seating suriace, and a bearing swivel plate disposedbetweenoneendoiaaidlpiingandsaid second-mentioned'abutment means to attain bdcal spring disposed about said plunger bearing against said abutment means,.other abutment means mounted on said plunger having ajapered seating V posed between one end of said spring and said second-mentioned abutment means and having a tapered contacting surface cooperating with said tapered seating surface to attain balanced spring action and avoid cooking of said.- plunger.

21. In a high pressure fluid pump the combination comprising, casing means having a plunger bore, spring abutment means fixed relative to said casing means, a pump plunger in the bore, a hellcal spring disposed about said plunger bearing against said abutment means, a collar slidably mounted on said plunger having a skirt radially spaced from said plunger and a tapered seating surface, a bearing swivel plate having a tapered contacting surface engaging the tapered seating surface of said collar with one end of said spring supported by said plate, said plunger having a shoulder within the collar skirt, and meanseon 1 filled between said shoulder and ma skirt deplunger.

mountably to fix said collar relative to said and avoid. cooking 5 said suriac'e, and a bearing swivel plate dis-v am 'n 'raaa. 

